In radio communication standards as for example in IEEE 802.16e, two or more base stations are synchronized to a same time basis. The base stations transmit synchronized downlink frames to mobile stations located in the coverage area of the base stations. In an overlap area belonging to two or more base stations the synchronized downlink frames of neighbour base stations can comprise resource blocks, which comprise the same data for a specific mobile station.
In collaborative MIMO (MIMO=multiple input multiple output) with multiple antennas at the transmitter and the receiver, two or more base stations collaborate in the downlink direction to send simultaneously radio signals in a same frequency band to a mobile station. In that way, the data throughput of the individual transmitters CaO be incremented, even if each base station has only a single antenna.
In a method for data synchronisation especially for collaborative MIMO an OFDMA radio communication system (OFDMA=orthogonal frequency division multiple access) comprises a network element coupled to at least a first and a second base station. The first base station is a master base station and the second base station is a slave base station of the master base station. The master base station and the slave base station are coupled to at least one wireless terminal. The relevant steps according to this method are: receiving a collaborative MIMO connection request from the wireless terminal by the master base station or the slave base station, sending a duplication signal to the network element from the master base station or the slave base station, the duplication signal indicating a duplication of a collaborative IP flow (IP=Internet Protocol) for the wireless terminal, receiving a first IP packet of the collaborative IP flow by the master base station and scheduling a first portion of a first downlink frame, sending a frame layout message from the master base station to the slave base station, the frame layout message containing a description about the first portion of the first downlink frame, and scheduling a second portion of a second downlink frame by the slave base station with the description of the first portion of the first downlink frame.
The way of scheduling data to a downlink frame by a base station affects the overall data rate of the base station. Therefore, it is the object of the invention to improve the data throughput of base stations using such portions hereinafter called parts in the downlink frame.